With the intensification of the world energy crisis, reducing energy consumption and protecting environment have become a consensus. In order to improve the efficiency of AC/DC and DC/DC power converters, half bridge, full bridge and LLC resonant converters have been widely used. But the operating frequency of the resonant converter varies with the dynamic changes of the load. The impedance of the gate, and the body-diode reverse recovery time (Trr) may impact on the dead-time control and even change the drive-signal waveform. Up to now, due to the fixed dead-time control, the zero-voltage switch (ZVS) may not be achieved if the dead-time is too long; the short-circuit may take place on one arm of the bridge if the dead-time is too short, less than a body-diode Trr, which may led to the failure of the resonant converter.